A large log file mostly indicates that a program or your system really has some problems. If you have large log files, then you can delete these but first check the log files. But if you do have a problem and want to delete the cache of some programs, you can click on the folder icon and search for that program and delete it this way. This will NOT save you some precious space on your disk.
If you delete them, your program will not only start slower but will REGENERATE the cache files again. Cache files are what makes your program load faster and perform tasks faster. The developer does NOT recommend you to delete ALL of your cache (or cache of some specific programs). Clean Me is a small macOS app that acts as a system cleaner (logs, cache, etc.) Read this first
